Field of the Invention
This invention belongs to the field of fine chemicals, in particular, the invention relates to methods and applications for synthesizing cationic bleach activators via a single-bath reaction.
Description of the Related Art
Hydrogen peroxide is a widely used bleacher in industry because of its environment-friendly and pollution-free properties. However, traditional bleaching methods of hydrogen peroxide have many shortcomings that limit their widespread application. Nowadays, there is a new bleaching method that uses hydrogen peroxide at lower temperatures. Compared with traditional methods, the new bleaching method is applied in nearly neutral environment (pH 11-12 in traditional methods by adding sodium hydroxide or sodium carbonate) and room or moderate temperature (about 100° C. in traditional methods). The new method has obvious advantages over the traditional ones, such as reducing the consumption of energy resources, lightening the workload on treatment of waste water, and decreasing the damage to bleaching substrates.
Bleach activators play an important role in the system of low-temperature bleaching. As an organic peroxy acid precursor, the bleach activator reacts with hydrogen peroxide in aqueous solution and produces peroxy acid which is more active than hydrogen peroxide, and can effectively eliminate colored impurities at a lower temperature. Sodium nonanoyloxy benzene sulfonate (NOBS), tetraacetylethylenediamine (TAED) and N-[4-(triethylammoniomethyl)benzoyl]lactam chloride (TBLC) are activators widely used during the bleaching process. However, the application of NOBS and TAED is limited because of some disadvantages such as side effects at near-neutral pH (e.g. NOBS) and low solubility (e.g. TAED). In contrast, TBLC has no disadvantages stated above. The optimum pH of TBLC is 7.2, and solubility of TBLC is excellent. At the same time, the quaternary ammonium salt cationic group of TBLC provides good affinity to negatively charged cellulosic fibers in aqueous solutions, which is helpful for enhancing the bleaching performance. However, high production cost and complex manufacture procedures are the main reasons impeding current application of TBLC in the industry. As for studies on TBLC like activators, many researchers are focusing on optimizing structures of the activators or modifying the bleaching procedures, for example, changing the carbon number of lactam loop of TBLC in order to increase hydrolytic stability or changing the structure of quaternary ammonium salt cationic group to synthesize activators of different or specific structures (e.g. dicationic structure) to investigate their application properties. Researchers found that the bleaching effect of (TBCC)—H2O2—NaHCO3 at 60° C. is similar to that of H2O2—NaHCO3 bleaching system at 90° C. In addition, the TBCC—H2O2—NaHCO3 bleaching system can improve hygroscopicity of cotton fabrics. However, there are few researches on simplification of the TBLC synthesizing process to decrease the production cost and expand the application scope.
Therefore, there is a need in finding simplified methods for synthesizing TBLC. The present invention satisfies such a need and provides other advantages as well.